This drug, Buy Fioricet 40 mg online, is used to treat tension headaches and other primary headaches. Paracetamol is a fever and analgesic. The effects of paracetamol are enhanced by caffeine. Barbiturates or acetaminophen, caffeine, and butalbital are classes of drugs. It works by slowing the nerve impulses in the brain that cause migraines and cluster headaches.